Nanoindentation into single-crystalline Si is modeled by molecular
dynamics simulation using a modified Tersoff potential. We observe that
the high stress produced during indentation leads to three processes
occurring consecutively in the substrate: (i) phase transformation of
the original cubic diamond (cd) to the bct5 phase; (ii) generation of
dislocations; and (iii) amorphization. The bct5 phase develops along
111 planes of the cd phase; when these meet, the enclosed volume of cd
phase transforms to bct5. The particular role played by a stable
tetrahedral structure formed by bct5 111 planes and 111 intrinsic
stacking faults in the cd structure is highlighted. The phase
transformation to bct5 is partially reversed when dislocations nucleate
in the cd phase and locally relieve stresses. The generation and
reactions of the uncommon dislocations 1/4 < 111 > and 1/3 < 112 > are
discussed. (C) 2016 Elsevier B.V. All rights reserved.